配列の配列について

$array_of_array = @(
@(
'1-1'
'1-2'
'1-3'
),
@(
'2-1'
'2-2'
)
)
$array_of_array | foreach {
Write-Host 'L1' $_
$_ | foreach {
Write-Host ' L2' $_
}
}
結果は期待通り
L1 1-1 1-2 1-3
L2 1-1
L2 1-2
L2 1-3
L1 2-1 2-2
L2 2-1
L2 2-2